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-rw-r--r--lib/ui/stack.go73
1 files changed, 73 insertions, 0 deletions
diff --git a/lib/ui/stack.go b/lib/ui/stack.go
new file mode 100644
index 00000000..9f81db8e
--- /dev/null
+++ b/lib/ui/stack.go
@@ -0,0 +1,73 @@
+package ui
+
+import (
+ "fmt"
+
+ tb "github.com/nsf/termbox-go"
+)
+
+type Stack struct {
+ children []Drawable
+ onInvalidate func(d Drawable)
+}
+
+func NewStack() *Stack {
+ return &Stack{}
+}
+
+func (stack *Stack) OnInvalidate(onInvalidate func (d Drawable)) {
+ stack.onInvalidate = onInvalidate
+}
+
+func (stack *Stack) Invalidate() {
+ if stack.onInvalidate != nil {
+ stack.onInvalidate(stack)
+ }
+}
+
+func (stack *Stack) Draw(ctx *Context) {
+ if len(stack.children) > 0 {
+ stack.Peek().Draw(ctx)
+ } else {
+ cell := tb.Cell{
+ Fg: tb.ColorDefault,
+ Bg: tb.ColorDefault,
+ Ch: ' ',
+ }
+ ctx.Fill(0, 0, ctx.Width(), ctx.Height(), cell)
+ }
+}
+
+func (stack *Stack) Push(d Drawable) {
+ if len(stack.children) != 0 {
+ stack.Peek().OnInvalidate(nil)
+ }
+ stack.children = append(stack.children, d)
+ d.OnInvalidate(stack.invalidateFromChild)
+ stack.Invalidate()
+}
+
+func (stack *Stack) Pop() Drawable {
+ if len(stack.children) == 0 {
+ panic(fmt.Errorf("Tried to pop from an empty UI stack"))
+ }
+ d := stack.children[len(stack.children)-1]
+ stack.children = stack.children[:len(stack.children)-1]
+ stack.Invalidate()
+ d.OnInvalidate(nil)
+ if len(stack.children) != 0 {
+ stack.Peek().OnInvalidate(stack.invalidateFromChild)
+ }
+ return d
+}
+
+func (stack *Stack) Peek() Drawable {
+ if len(stack.children) == 0 {
+ panic(fmt.Errorf("Tried to peek from an empty stack"))
+ }
+ return stack.children[len(stack.children)-1]
+}
+
+func (stack *Stack) invalidateFromChild(d Drawable) {
+ stack.Invalidate()
+}